1. Field of the Invention
The present invention generally relates to a belt-driving apparatus for driving an endless belt that is used in an intermediate transfer unit, a transfer-and-separation unit, a transport unit, charging unit and a developing unit for electrophotographic copying machines and printers, and an image forming apparatus that uses the belt-driving apparatus.
2. Description of the Related Art
A conventional tandem type electrophotographic image-forming apparatus uses a belt unit that transports a medium on which an image is transferred by an electrophotographic process. This type of belt tends to snake. For this reason, a projected guide is provided on an inner surface of the endless belt for preventing the belt from snaking. The belt runs with the projected guide received in a pulley, so that the belt runs without snaking. The belt guide is formed of a reinforcing material having a tensile modulus of more than 5,000 kg/cm2, a layer of adhesive having a thickness in the range of 5 to 100 μm, and a material having a hardness in the range of 30 to 95 Hs (JISA) bonded to the layer of adhesive.
The aforementioned conventional apparatus suffers from the problem that the endless belt comes off the belt guide or the belt guide may break.